Two House banks

[nwboater]

Salty’s 12VDC system is powered by (2) Fullriver 4D AGMs (440Ah house bank). Instead of adding an inverter to the house bank, I’ve taken a different approach: To provide 120VAC, I installed a 4.5Kw lithium power station (Hysolis) with built-in 3000 watt inverter. When we leave the marina I plug the Hysolis into the my boat’s shore power receptacle. In this way, the lithium power station is completely separate from the 12V system. The Hysolis can be charged by the generator or from shore power. The house bank can be charged by alternator or by the Hysolis powering the ship’s 50Amp ProMariner charger. With no inverter load on the house bank, this arrangement has added greatly to the practical capacity of the house bank. Best if all, it provides ample power for all of our AC needs — Think of it as “portable shore power”.

 

[Lepke]

One reason for multiple banks is how fast you charge.

I had 3 8d banks of 48v for my inverter and they were different ages. If I let my inverter charge all 3 at once it divided the charge among the banks and older batteries didn't fully charge. It also took a long time to charge. So I bought 2 chargers and when running a generator or at the dock all 3 banks had a dedicated charger. The diesel saved by running the generator fewer hours paid for the chargers. It would save even more now.
At anchor I use the banks one by one and can go as long a 5 days w/o running an engine.

 

[catalinajack]

So many boats, so many answers, most of which are not right or wrong, just different. Here is what I have.

One 920Ah bank of flooded batteries that also serves to start a pair of Lehman 120s (no dedicated engine starting batteries). Two generators with their own starting batteries, which can be used to start the Lehmans in the event I am downright dumb enough to deplete the house bank too much. Fewer switches, far less wiring. Charging is done with a pair of externally regulated 100-amp (nominal) alternators. The generator starting batteries are charged through an ACR, but for the amount of current they draw when starting a generator, I could probably start them 10 times without recharging. Plus, the generators also have their own charging capabilities. My bow thruster battery is charged through a second ACR, but I use the thruster only occasionally and then for just a few seconds.

Please, guys, no comments are needed on the starting battery redundancy preference. That subject has been discussed many times on this forum. I see no need for them, others do.

 

[catalinajack]

Salty’s 12VDC system is powered by (2) Fullriver 4D AGMs (440Ah house bank). Instead of adding an inverter to the house bank, I’ve taken a different approach: To provide 120VAC, I installed a 4.5Kw lithium power station (Hysolis) with built-in 3000 watt inverter. When we leave the marina I plug the Hysolis into the my boat’s shore power receptacle. In this way, the lithium power station is completely separate from the 12V system. The Hysolis can be charged by the generator or from shore power. The house bank can be charged by alternator or by the Hysolis powering the ship’s 50Amp ProMariner charger. With no inverter load on the house bank, this arrangement has added greatly to the practical capacity of the house bank. Best if all, it provides ample power for all of our AC needs — Think of it as “portable shore power”.View attachment 135042View attachment 135043

That is an interesting solution, but what I see is that you have merely added a second house bank. You could reach the same place by simply increasing the size of your 440Ah house bank, which may be going underutilized. Also, the Hysolis uses a Li(NiCoMn)O2 battery, not the much safer LiFePo4 lithium batteries.

 

[Mako]

I think about my previous big boat. Twin diesel and twin gensets. It had two house banks (4-8Ds each). All engines were fed by these banks, so when I ran the 3kW inverter it was either off bank 1 or 2, but never both.

However my personal preference would be along the lines of what Catalinajack described. One large house bank which would also act to start the main engine(s). This assuming it is 24v of course.

The genset only needs a tiny 12v battery for starting, and provides the redundancy needed.

It would be nice if someone developed 48v starters.

EDIT - Actually, I recall that the automobile industry has developed 48v dual-purpose starter-generators. It's an interesting concept, to start your diesel and then have a "shaft generator" backfeeding power as well.

 

[sunchaser]

. Actually, I recall that the automobile industry has developed 48v dual-purpose starter-generators. It's an interesting concept, to start your diesel and then have a "shaft generator" backfeeding power as well.

Good point. There are several auto models out there doing this exactly. Notably Volvo with their hybrid setups. Excepting Volvo, there are few other marine engine builders out there that could easily adapt this new technology, or for that matter see the profit potential to do so on the marine side.